ok now, i have a flowmaster catback on my 2001 trans am i bought the car with the exhaust in it already. but i keep hearing everywhere how bad it is. i dont understand why that is i always knew flowmaster to make great exhausts in the muscle car department, but everyone says it sucks for our ls1's. now what i wanna know has anyone did any kind of flow test on the exhaust to prove that it is bad flowing or flows less than others. and not comparable to the other aftermarket exhausts, i know loudmouth/gmmg will be better sense it is a straight through muffler but please someone show me proof so i can put my mind at ease lol. the exhaust sounds so good on the car and id hate to change it out in the future for no reason just because a bunch of people had a thing against it but it was false to much money to be wasting if its not true. so anyway lemme see some proof please

 

read this thread of my dyno...

https://ls1tech.com/forums/dynamometer-results-comparisons/427836-dyno-numbers-speed-inc-2001-z28.html

My dyno would have been higher minus the dirty air filter, but it was 10rwhp lower with the cutout closed.

Also notice the other post further down where a dude was losing huge power because of his flowmaster compared to when his cutout was open!

Even since I installed LTs and an ory, i have kept my cutout open (which is too loud for city driving). I have kept the cutout open because you can hear the restriction the flowmaster is causing now that my LS1 engine can breathe more.

I get alot of interior drone and vibration when the going through the flowmaster, which proves how restrictive they are. Also look at an internal picture of one, its all weld in baffles that dont allow for direct airflow!

I will be installing a magnaflow or hooker aero chamber soon! Yeah the flowmaster sounds great but flow terrible. Many other systems sound great and flow as well as cutout, especially with headers!

 

yeah but i would expect a cutout to give more hp on any catback exhaust, i wish someone had a dyno of a flowmaster then another catback on

 

That sums up flowmaters. I bought my car used and it already had a flowmaster on it. I thought I was the **** until I went to the speed shop and they asked what catback I had and I said flowmaster and the laughed then told me I was SOL. I had them install hooker headers and ORY and a Qtp cut out. My car sounds great now and I dont think I will be getting rid of the flowmaster becasue that would be pointless. Sounds great and when I want to go fast I just open the cut out.

 

Yeah, but with a LM or Magnaflow among others, you will lose more like 1 rwhp. The more power you make, the more you will lose with the flowmasters. I know a guy who says he loses 25rwhp through his flowmasters vs. open cutout. It shows up on the track also. He's so loud that sometimes they make him close his cutouts, and it makes a big difference in his timeslip.

 

if its the 80 series crossflow, you have a poor flowing exhaust.

for a stock ls1 a flowmaster is fine because its about as good as the stock muffler but as you build up the engine the more it will restrict and the more you will lose out on power.

Due to the internal V shape baffles that flowmaster welds into their muffler, you looking at an obstruction in air flow that results in about +100cfm loss as compared to a good mufler system.

A cutout will always show huge gains over flowmaster 80series but will show very very minimal if any gains over a high flowing muffler, like GMMG, magnaflow, borla or slp LM.

I dont like the fact that I wasted $350 on a flowmaster and now I will be spending another $300-400 for a better system but I dont like hearing the restriction when I drive my Z and knowing that I am losing power because of it!

 

Imagine trying to blow through a straw that has a bunch of walls, baffles, and edges. You're obviously not going to have much luck. This is how your car feels when you have a Flowmaster 80 series on it.

 

lm sounds better than flowmaster anyway.. i had a flowmaster muffler and switched to a lm, it sounds sooo much better IMO

 

yes,the 80 series is terrible for flow. the muscle car flowmasters you're talking about are alot better than these cross=flow junkers.

 

ok i get it i supose i think i want a GMMG anyway i just thought id ask hehe

 

LOL nothing wrong with that, GMMG are expensive. Have you considered or thought about true duals and headers?

 

wouldnt true duals wind up be just as exspensive and maybe harder to find becuase not many placed mandrel bend pipes

 

My car came with a flowmaster cat back too. I didn't like its highway drone much with the stock exhaust manifolds and y pipe. I did start my car up with it still in place after I installed my headers and off road y pipe and it sounded great, but I never drove it before putting on a hooker aerochamber cat back. If I had to do it over again I may have just got an electric cutout. If you are going to look at replacing it look into the hooker system as it is cheap and has a good reputation around here.

 

rgaynor85 "wouldnt true duals wind up be just as exspensive and maybe harder to find becuase not many placed mandrel bend pipes"

TSP makes a great TD system. I just ordered them for a great price ( ill pm you the price) shipped to my door. I had LT's and LMII and it I liked it but i heard a td f body and there was no way mine sounded as good as his did. plus im sure they flow a lil better. as far as price as I said before Ill pm you a total price.

 

That's what I'm getting too.

 

TSP rumbler.. 200$.. cant beat that deal anywhere...

 

a mandrel bent x-pipe, bullet style mufflers and turndowns before the axle is about if not cheaper then gmmgs!!

 

Flowmaster and LS1 do not mix.

 

I just put mine on last Friday. I think it sounds even better in person. After hearing it in person finally, IMO it's the only option for an LS1. I've been driving around in circles with my windows down LOL. I think it's gonna be pretty loud when the pacesetters go on though. I already set off a few car alarms.

 

I'm in the same situation with the Flowmaster setup. I've got Kooks LT's and ORY and considered the TSP Rumbler X, but was cocerned that it would be too loud on the interstate. I like being able to hear the radio. I like the way the TDs sound, but that's my only worry. Thought about the Magnaflow or GMMG too, but never have heard one in person. Everybody around home runs SLP systems.